Biosensors and Bioelectronics 31 (2012) 176–181 Contents lists available at SciVerse ScienceDirect Biosensors and Bioelectronics jou rn al h om epa ge: www.elsevier.com/locate/bios Enzymatic glucose biosensor based on CeO 2 nanorods synthesized by non-isothermal precipitation Dewyani Patil ∗ , Nguyen Quoc Dung, Hyuck Jung, Se Yong Ahn, Dong Mi Jang, Dojin Kim ∗ Department of Materials Science and Engineering, Chungnam National University, Daejeon 305-764, Republic of Korea a r t i c l e i n f o Article history: Received 15 September 2011 Accepted 8 October 2011 Available online 17 October 2011 Keywords: Glucose biosensor CeO2 nanorods GOx Amperometric biosensor EIS behavior a b s t r a c t Cerium oxide nanorods (CeO 2 NRs) were synthesized without templates through a low cost and simple non-isothermal precipitation method. The structure and morphology of CeO 2 NRs were characterized by X-ray diffraction and transmission electron microscopy. The CeO 2 NRs films, deposited on indium tin oxide (ITO)-coated glass substrates through electrophoretic deposition, were used for the immobilization of glucose oxidase (GOx). Field emission scanning electron microscopy, Fourier transform infrared spec- troscopy, cyclic voltammetry, and electrochemical impedance spectroscopy were used to characterize the CeO 2 NRs/ITO and GOx/CeO 2 NRs/ITO electrodes. The GOx/CeO 2 NRs/ITO electrode exhibits a linear range for the detection of glucose from 2 to 26 mM (correlation coefficient: 0.99) at 1–2 s response time. Biosensor sensitivity is 0.165 A mM -1 cm -2 with 100 M detection limit. The anti-interference ability of the biosensor was also examined. The mediator-less application of CeO 2 NRs for glucose sensing was demonstrated. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Biosensors such as glucose biosensors have received great atten- tion owing to applications in clinical chemistry, biological, and chemical analyses, the food industry, and environmental moni- toring. Several attempts have been made towards the fabrication of a biosensor for the estimation of glucose with glucose oxi- dase (GOx); most of these attempts use conducting polymers (Gvozdenovic et al., 2011; Patil et al., 2007) and semiconduct- ing metal oxides (Chaniotakis and Sofikiti, 2008) to immobilize GOx. Recent studies reveal that the nanostructured metal oxides with reduced dimensionality (i.e., nanoparticles, nanorods, nan- otubes, nanowires, and nanoribbons) have unique advantages in immobilizing enzymes and have high sensitivity due to high sur- face area, desirable microenvironment, and direct electron transfer between enzyme active sites and the electrode. Various nanostruc- tured metal oxide materials (Liu, 2008; Ansary and Faddah, 2010) such as nanostructured ZnO in the form of nanorods (Asif et al., 2010), nanowires (Pradhan et al., 2010), nanotubes (Kong et al., 2009), nanocombs (Wang et al., 2006), nanofibers (Ahmad et al., 2010), CuO nanorods (Umar et al., 2009), TiO 2 nanotubes (Pang et al., 2009), and ZrO 2 nanoparticles (Yang et al., 2007) have been utilized for the fabrication of enzyme-based biosensors. However, glucose sensors based on nanostructured ZnO exhibit interference ∗ Corresponding authors. Tel.: +82 42 821 6639; fax: +82 42 823 7648. E-mail addresses: pdewyani@yahoo.in (D. Patil), dojin@cnu.ac.kr (D. Kim). caused by uric and ascorbic acid (Zhai et al., 2010). ZrO 2 nanopar- ticle glucose biosensors use ferrocenium hexaflurophosphate as the electron transfer mediator (Yang et al., 2007), whereas TiO 2 nanotubes use covalent bonding to immobilize GOx (Zhang et al., 2011). Nanostructured CeO 2 is one of the most promising materials for the fabrication of electrochemical biosensors due to interesting properties such as chemical inertness, nontoxicity, biocompatibil- ity, high specific surface areas, electrical conductivity, and high electron transfer features. It has a wide band gap (3.4 eV) and a high isoelectric point (IEP) of about 9.2 (Ansari et al., 2008a,b), making it suitable for the adsorption of low IEP enzymes such as GOx (IEP4.2) (Yang et al., 2009) without the need for any harsh chemical treatment. Few reports deal with nanostructured CeO 2 -based glucose biosensors. Ansari et al. reported a glucose sensor based on immobilized-GOx sol–gel derived from the nanos- tructured CeO 2 /Au bioelectrode using a Fe[(CN) 6 ] 3-/4- mediator with high sensitivity (0.00287 A mg dL -1 cm -2 ), linearity in the range of 50–400 mg/dL, high detection limit (12 M), and sta- bility for 12 weeks (Ansari et al., 2008a,b). Saha et al. recently reported the synthesis of nanoporous CeO 2 thin films on platinum- coated glass plates (i.e., nanoporous CeO 2 /Pt) using pulsed-laser deposition and investigated their glucose sensing properties. The GOx-immobilized nanoporous CeO 2 /Pt bioelectrode showed lin- earity in the range of 1.39–8.33 mM and a shelf life of 10 weeks (Saha et al., 2009). The present study reports on glucose biosensors based on the adsorption of GOx onto CeO 2 NRs. The CeO 2 NRs were synthesized 0956-5663/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.bios.2011.10.013